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TL1963A-15 questions

haohome
Prodigy 150 points


Hi Team,

Please help with this question, thanks!

Hi Hao,

I have a question about the LDO regulator TL1963A-15
I do not see the junction to pad resistance Θj-p for the SOT-223-3 (DCY package) and SOT223-5 (DCQ package)? could you give me these numbers
The specified junction to case resistance Θj-c,  is it between the junction and the plastic case?
How the Θj-c of DCQ package (15°C/W) is half the Θj-c of DCY package (30.6°C/W), while they pad area does not have the same ratio (I know it does not have to be exactely the same ratio)?

regards
Mickel Chehoury
Sr. hardware design engineer
Safran Electronics Canada Inc.
P.O. Box 4525, 2000 Fisher Drive
Peterborough, Ontario
K9J 7B1
Phone: (705) 743-6903 Ext. 429
Fax:     (705) 745-1394
Mickel.Chehoury@safran-electronics.ca

  • 0
    TI__Expert 8890 points

    Hi Mickel,

    The thermal resistance measurements are calculated in accord with a JEDEC standard layout.  By that standard the theta_jc is measured at the top center of the package.  By that same standard the theta_jp is only measured on parts that have "exposed thermal pads" on the undersideof the part - like that of the KTT package.  Note that the theta_jp measurement is measured at the center of the underside of the part (somehow?). Since the DCQ and DCY packages do not have the exposed thermal pad "under" the part the JEDEC standard did not apply and the measurement was not made - even though it would have been a really good idea to have done so.  I asked a thermal/packaging engineer if it would be reasonable to estimate the theta_jp for these other packages to be approximately in the same ratio as that for the KTT package relative to theta_jc.  His response was that that would be a rough but adequate approximation given that the internal lead frames and construction for all three parts is very similar.

    Regards

    Bill